Proportioning pump



June 17, 1952 R. v. BURT 2,600,477

PROPORTIONING PUMP ATTORNEYS- June 17, 1952 R V, BUR-r 2,600,477

PROPORTIONING PUMP Filed Aug. 21, 1947. 5 sheets-shane d/www y ATTORNEYS.

June 17, 1952 R. v. BURT 2,600,477

PRoPoRTIoNING PUMP Filed Aug. 21, 1947 5 sheets-sheet 5' o J6' l 5b a' 8.M 55.11, 3/ 52 54 l .fz J6' EG.4. I I NVENToR.

f5 f6 BYLW y ATTO RN EYS,

R. V. BURT PROPORTIONING PUMP June 17, 1952 5 Sheets-Sheet 4 l l l Il Filed Aug. 21, 1947 ATTORNEYS.

June 17, 1952 Filed Aug. 21, l947| R. V. BURT PROPORTIONING PUMP 5 Sheets-Sheet 5 INVENTOR. offr l( .5u/f7:

ATTORNEYS.

Patented June 17, 1952 PROPORTIONING PUMP Robert V. Burt, Cincinnati, Ohio, assigner to The Procter & Gamble Company, Cincinnati, Ohio,

a corporation ofOhio Application August 21, 1947, Serial No. 769,820

(Cl. S-120) Claims. l

My invention relates to rotary pumps of the internal gear and external gear types. These are positive displacement pumps, and may be used as accurate meters of the materials pumped.

In such pumps a pair of gears divides an inlet chamber from an outlet chamber. The material being pumped is carried from the inlet chamber to the outlet chamber in pockets between the teeth of the gears, which pockets are closed by casing elements; and at the outlet chamber the meshing of the gears forces the material being pumped out of these pockets.

One of the objects of this invention is to provide adjustability in mechanisms of this class. The invention is based in part on the concept of means for shifting the gears relative to each other in the axial directions. This together with means for keeping the inlet chamber isolated from the exit chamber excepting through the pumping action of the gears, enables me to adjust or vary the actual displacement of the pump per revolution while retaining the advantage of positive displacement. The variation of actual displacement is thus accomplished through a variation in the axial extent of the meshing of the gears, which in turn controls the quantity of the material pumped or forced out of the pockets by the meshing action of the gears.

In another aspect of my invention, it is my object to provide, in a single device, a pair of pumping means, each driven concurrently at the same speed, each being adjustable as set forth above, but the adjustment of one being inverse to the adjustment of the other. Such a device may be employed to supply separate streams of different materials, which streams "bear a denite but accurately adjustable relaother gear, common to the two pumping sections, meshes with the individual gears.

Appropriate casing elements are provided in association with the individual gears, and a partition element co-acting with the common gear is provided to divide the pumping sections from each other. Provision is made for relative axial movement of the partition element and the common gear. Adjustment may be effected by -moving the common gear axially with relation to the individual gears, or by moving the individual gears and their related casing elements with respect to the common gear. It will be seen, however, that in such adjustment, to the extent that the meshing engagement of the common gear with one of the individual gears is increased, its meshing engagement withv the other is diminished. Hence, the variationsof the displacement of thev pumping sections bear an inverse relation to each other. Since both pumping sections provide positive displacement, the proportion of the streams may be very accurately adjusted and maintained.

In another aspect of my invention, which will be later described, it is my object to provide pressure equalization between the inlet and outlet of my fpump thus increasing its accuracy as a meter while depriving it of the function of impelling or pumping the liquid passing through it. Since in its broader aspects my invention may iind use either with or without this pressure equalization attachment, I use the term pumpf either as noun or verb, when referring generally to the delivery of liquid through intermeshing gear devices of the character here dealt with, whether the liquid be independently-impelled or not.

While there are many varieties of positive displacement pumps, it will sufce for an explanation of my present invention to-describe it in connection with a pump mechanism of the external gear type and a pump mechanism` of the internal gear type. The principal objects of my invention which have been set forth above, and others which will be pointed out hereinafter. or will be apparent to one skilled in the art upon reading the specifications, I accomplish by that structure and arrangement of parts of which I shall now describe the aforesaid exemplary embodiments. Reference is made to the accompanying drawings wherein:

Figure l is a vertical. longitudinal, sectional Aview of one form of my pump when of the internal gear type. lIt is a section taken along the line Figure 3 is a transverse vertical section taken along the line 3-3 of Figure 1.

Figure 4 is a partial section through the rotor elements of one of the pump sections.

Figure 5 is a perspective view of one of the movable casing elements.

Figure 5a is a perspective view of the partition element and its associated parts.

Figure 5b is a horizontal cross section taken on the line 5b-5b of Figure 3.

Figure 6 is a vertical longitudinal section through a pump of my invention which is a pump of the external gear type. It is a section taken along the line 6-5 of Figure '7.

Figure 7 is a transverse vertical section-through the same pump taken along the line 'I-'I of Figure 6.

Figure 8 is a transverse vertical section taken along the line 8-8 of Figure 6.

Figure 9 is a transverse vertical section taken along the line 9-9 of Figure 5. l

In Figures 1 and 2 I have shown a housing formed in two parts -50 and Il which may be bolted together by means of. flangesas shown. These housing parts arecongured to provide a central cylindrical chamber I2 formed by the matingparts of each housing element. In addition each housing element. provides anY outlying oval chamber I3 or I4. (The cross sectional shape of these chambers might more accurately be described asv being formed of two serni'circles connected by parallel straight lines.)

A common gear, I5, which is hollow and' has internal gear teeth I6 on its inner periphery, is mounted in the cylindrical chamber. Centrally 'it is provided with `external gear teeth I1. These teeth mesh with a gear I8 on a shaft I3, journaled as at 2U and 2| in a portion of the housing element I0. A vportion ofthe shaft. I9 projects as at Iga from the'housing element i0. The `projecting portion may be provided with a suitable Vdrive connecting it to Ia prime mover. The shaft vof the oval chambers i3 and I4 maintain a xed axial position'for the common gear I5.

A pair Yof individual gears 24 and- 25, in axial alignment, and provided with external gear teeth, mesh with the common gear I5. These individual .gears are rotatably'journaled upon a shaft 25 `extending longitudinally of the device. Thisshaft j., passes through casing elements indicated at 21 and 28. The form-of these. casing .elements is *shovvne in perspective in Figure 5. Each casing element'has a central hub as'indicated at` 29 to accept the shaft 26.V The hub is pari-,oi a body indicated at 30a At the outer end. of the body thereis a i-'lange 3l shaped toi-t the inner-peripheryA of the oval chambers I3. or i4.. Upwardly from the hub there extends afin 32v the purpose of which. isto provide, in part,. a means for. dividing the entrance chamber -fromthe exit chamber in the. particular pump section in which the casing Ais. located. The inner end of the casing is p rolonged as at 33. The length of this prolongation is the same as the Width of the individual gear 24 or 25. with which the casing element 1s used.

"The shape of the prolongation is lunar, as shown. ,The shaitr23 passes through the hub 29 and .is ,preferably splined. to it. Inthis way the casing members 21 and 23 can holdthe shalt 26 against rotation. The individual gears 24 and 25 are mounted on the shaft and lie above the projections 33 and 33a.

It will be seen in Figure 1 that the shaft 26 passes through both casing members 21 and 28. The shaft is provided with an enlargement 26a intermediate its ends. This enlargement is -an eccentric, and it serves to mount rotatably a partition element 34. The partition element has external teeth meshing with the internal teeth of the common gear I5. Its outer periphery is the same as the inner periphery of the common gear, and it rotates with the common gear on the eccentric 2G which gives it a pivot co-axial with the pivot of thecommon gear. The partition gear element 34 is, however, slidable with respect to the common gear I5.

The position of the partition element 34 on the eccentric a is maintained in part, as shown, by the projections 33 and 33a on the casing elements 21 and 28 and inpart by the individual gears 24 and 25. Suitable wear rings maybe employed. The assembly of casing elements, individual gears and partition gear element may be held together on the shaft by nuts 35' at one end and by a collar .36 at the other; and it Will be understood thatthis entire assembly Amay be shifted longitudinally or axially `with respect tothe common gear I 5,.the partition element 34.fo1lowing the individual gears 24 and 25.

The shaft 26 is continued through -oneend of the housing element I4, Which is provided with aeap 3l. An internally threadedsleeve 38, journaled in a barrel-like extension-39A of the cap 3l, engages the projecting end of the shaft 25. This .shaft is threaded. The. sleeve 313 is provided with a handWheel-d by means of which itmay be turned. Turning vthis sleevewill move the shaft 26 longitudinally of the pump housing, carrying with it .the casing elements 21 and 28,`the individual gears 24and 25, and the partition element 34. To give .an accurate indication ofthe longitudinal. position of theshaft, I provide the sleeve 3B -With aninternally threaded barrel 4I extending over an externally threaded sleeve 4I@ which loosely encircles the barrel-like extension 39, and IInark'these elements 4I and Ala with appropriate indicia.

The casing elements 21 and 28, where they slide in the oval chambers I3 and I4 maybe provided with packing rings 42 and 43. The end of the housing element I3 may be closed with a cap 44. This cap may be provided with an inwardly extending, hollow nozzle lying Within a bore 46 in the shaft 2'6. The nozzle 45 may have a liquid tight and pressure tight engagement Within the bore 46 bymeans of seal rings li-'I or the like. The bore 4S terminates in a passageway 48 extending longitudinally of the shaft 25, and providedl With cross-passageways 49 and 58 to lubricate the bearings of the individual gears 24 and 25 on the shaft, and a cross-passageway 5I to lubricate the bearing. of the partition element 34 on the eccentric enlargement 26a of the shaft. TheI chambers I3 and I4-may be provided with clean-out openings |,3a and I 4a passing through .the Walls of housingv Velements Ii] and Ii.

As shown in Figure 3, each pump sectionis provided with inlet or outlet chambers `or passageways. Thus the housing element II iscongured to provide an inlet chamber 52 provided with an inlet coupling 53, and an'outlet chamber 54. These passageways or .chambers are kept separate in part by the coacting gears I5'and. 25

in their meshing position and in part by the coaction of a portion 55 of the housing and the n 32 of the casing element 28. The passage of material to be pumped from the inlet chamber 52 to the outlet chamber 54, is in the pockets between the internal teeth I6 of the common gear I5 and the pockets between the teeth of the individual gear 25, these pockets being closed by the lunar extension 33a of the casing element 28. This is illustrated in Figure 4; and it will be appreciated that this relationship is that obtaining in conventional internal gear types of positive displacement pumps. In my apparatus, however, by shifting the longitudinal or axial position of the shaft 26, I can shift the position of the individual gear 25 with respect to that of the common gear I5. This varies the longitudinal area of meshing of these gears, and changes the specific displacement of the pump section. The effective volumes of the pockets aforesaid do not change; but the amount of material displaced from these pockets by the meshing of the gears at the outlet side of the pump does change with the relative longitudinal positions of the gears, and hence the displacement of the pump section changes in the Way set forth above. Further, it will be noted that the individual gears 24 and 25, together with their appropriate casing sections, move as a unit with respect tothe common gear I5. Hence as the length of the meshing engagement of the individual gear 25 with common gear I5 increases, the length of meshing engagement of the individual gear 24 with the common gear I5 decreases, the partition element 34 moving with the individual gears. Thus, the particular displacement of one pump section is increased at the expense of the particular displacement of the other pump section in an inverse relationship. An accurate proportioning of the streams is thus obtained, irrespective of the actual speed of the pump.

In Figure 3, I have shown another housing element 56 attached by iianges to the top of the housing element II. The portion 56 is so configured as to provide a chamber 51, connected with the outlet chamber 54, and lying directly above the inlet chamber 52, from which it is separated by a flexible diaphragm 58. This diaphragm is connected through suitable flanged bearing members to an upwardly extending valve stem 59, terminating in a valve element 6I! having truncated conical shoulders at 60a and 60h each surmounted by a guide portion of web shaped cross section (as shown in Fig. 5b). These shoulders coact with valve seats. in the ywalls of the outlet passageway 5I This passageway may be provided with coupling means 62. Pumped material in the outlet chamber 5'! can get into the passageway 6I only through the variable openings 60a and 60h. The position of the valve stem 60, and thus the size of the openings at 60a and 60h, is controlled by the opposing pressures on the opposite sides of the diaphragm 58, i. e. the pressures in the inlet chamber 52 and the outlet chamber 51. The pressure in the outlet chamber 51 in turn is controlled by the size of the openings at 65a and 60h. Since the eiective areas of the lower and upper surfaces of the diaphragm 58 and the valve members attached thereto are substantially equal, this arrangement results, when the pump is delivering liquid supplied to it under positive pressure, in the valve stem 5I! taking a position which restricts the openings 60a and 60h enough t0 create a back pressure in the outlet chamber 5.1 substantially equal to the externally imposed pressure on the fluid entering the inlet Vchamber 52. Thus the liquid is metered through the pump, but not impelled thereby, from the inlet chamber 52 to the outlet chamber 51 with essentially no gain or loss in pressure. This circumstance tends to eliminate any tendency for leakage or short circuiting of the liquid past the ends of the gear wheels or betweenthe ends of the gear teeth and the surrounding housing members or along other undesired paths, even though the supply pressure in the inlet chamber 52 fluctuates rather widely, or even though the several partsof the pump have worn to such an extent that the clearances are more than the minimum working clearances. A manually operated means for forcing the valve stem 6B into a position such that the valve spaces at 60a and 60h are open, for cleaning purposes or when using the metering re Vice as a true pump, is indicated at 63. A similar pressure control housing element and appurtenances indicated at 56a in Figure 1 is provided for the other pump section.

Other forms of displaceable barrier between` inlet and outlet chambers, to control the opening of a valve regulating the passage of liquid through one of these chambers, may be employed if desired.

Although the metering pumps herein described may be operated so as to impel the liquid being metered, thus serving the dual purpose of a true pump and meter, I prefer for greater accuracy of metering to impel the liquid by some independent means, such as a separate delivery pump in the line ahead of the metering pump, or a constant head liquid supply tank. Furthermore I nd that the most satisfactory results are obtained when the liquid to be measured is delivered to the metering pump at a substantially constant pressure, and also when the metering pump discharges themetered liquid against a substantially constant back pressure, which may conveniently be provided by means of an adjustable pressure regulating valve in the discharge line. l

In Figures 6 to 9 inclusive I have illustrated the principles of my invention applied to a gear pump of the external gear type, which is also preferably provided with pressure equalizing attachments as described above. In this external gear metering device the common gear 64, instead of being the driving gear, is driven by the individual gears and B6. Also instead of being fixed longitudinally of the housing members, the common gear moves in this embodiment, while the individual gears remainl in the same positions with respect to the housings.

I have indicated a pair of housing members at 61 and '38. These are bolted together by means of ilanges as shown. 'Ihey are congured internally to provide oval chambers 69 and 1I).

The common gear B4 is rotatably mounted upon a non-turning shaft 1I. At the ends of the common gear there are casing members 12 and 13. The outer ends of these members are of oblong configuration and entirely fill the cross-sections of the chambers 69 and 1B. They may be provided with seal rings as indicated at 14 and 15. The inner ends of these members are shaped as indicated at 16 in Figure 8. The shaft 1I passes through these casing members, which, together with the common gear 64 .form a unit movable as such in the chambers-'69 and 7 TIB. The :shaft 'Il is preferably splined to the casing members 1.2 .and 13, and the assembly is held `:together by'means of nuts and va collar .as .described above. The same general 'type of lubricating means may be provided; and I also provide the same type of means for shifting the shaft 'Il longitudinally and the same type of 4micrometer means for indicating its position.

The individual gears Sand l(iii are splined to a shaft H. This shaft has :bearings 'I8 and '19in end caps 80 and 8l for the housing members. The projecting end of the shaft as at 11a .is connected to a suitable source of power. vIt will be noted also 'that the shaft 'i1 passes through the enlarged outer end portions of the .cas-ing members I2 and 13.

I also mount casing members 82 and 83 on the shaft 11. These casing members, which may be provided with seal Vrings as indicated at82q'and 83a, are circular in form as shown atA 82 in Figure 8; and the individual gears B5-and 66 together with the casing members 82 and 83 form a unit assembled -by collars on the shaft Ti.

In this embodiment of my invention the partition means comprises a plate 84 held between the anges of the main housing member. As `will be most clearly seen in Figure 9, this plate has a circular perforation 85 co-axial with Ythe shaft 1i. In this perforation I'journal a rotary partition member 86 having interior teeth meshing with the teeth of the lcommon gear 64. A-s the common gear Si moves axially, its surface can slide through this rotary partition member While the latter maintains its alignment with the stationary partition element 84. The partition is held in position partially by shoulders 0D the ends of the housing members and partially by engagement between the individual gears 65 and 6G, as will be apparent from Figure 6.

As shown in Figure '1, the housing elements S1 and 58 are further congured to provide an inlet chamber 8l and an outlet chamber 88. The material being pumped passes from the inlet chamber S-'I tothe outlet chamber 88 in the pockets between the teeth of the gears at the upper and lower portions of the housing, these pockets being closed by the housings. The meshing ofV the gears forces the pumped material outof the pockets in the outlet chamber B8. sections isolated from each other at all times; but by shifting the common gear 64, the extent of meshing of the common gear with either of the individual gears can be varied, and this variation will be inverse as respects the two individual gears. Thus while the volume of the pockets does not change, the amount of pumped material forced out of them by the meshing of the gears does change, and hence the specific delivery of each pump section per rotation of. thel drive shaft 11.

It will be seen that in both embodiments of my invention the combined lengths of the individual gears is substantially greater than the length of the common gear. In each embodimentA there are casing elements which move with the movable rotary element or elements and Serve as seals. In each case, there is a partition element continuously effective to seal one pump section from the other, but movable with respect to the common gear, though meshing and rotating with it.

Modi'cations may be made in my invention without departing from the spirit of it. Having The partition means 84 keep the pump thus kdescribed my invention in certain .exemplary embodiments, what I claim as new and desire to secure by Letters Patent is:

1. In .a pump, a housing having two sets of inlet and outlet chambers, a common gear in said housing, a pair of individual gears in said housing, each in meshing relationship with said common gear, means coacting with the teeth of said gears to close pockets formed between said teeth for the travel of material being pumped from said inlet chambers to said outlet chambers, andmeans for effecting a shifting of the axial positions of said common gear and said individual gears whereby to vary the axial extent of .the meshing'of said common gear with said individual gears inversely, and further means for dividing said sets of inlet and outlet chambers, said means comprising a partition element having teeth which maintain a continuous meshing with all of the teeth of said common gear, said element being rotatable with said common gear but slidable axially with respect to it, while maintaining a ilxed axial position with respect to said individual gears and extending in part at least between said individual gears.

2. The structure claimed in claim l, wherein said several gears are gears with external teeth, and wherein said rotating partition element is a member surrounding said common gear and having internal teeth.

3. The structure claimed in claim l, wherein said common gear has internal teeth, and wherein said individual gears have external teeth, said rotary partition element being a member located within said common gear, and having external teeth.

4. The structure claimed in claim l, wherein said several gears are gears with external teeth, and wherein said rotating partition element is a member surrounding said common gear and having internal teeth, and including casing elements within said housing slidable with respect to each other, and maintaining a xed relationship respectively with the ends of said several gears.

5. The structure claimed in claim 1, wherein said several gears are gears with external teeth, and wherein said rotating partition element is a member surrounding said common gear and having internal teeth, and including casing elements within said housing slidable with respect to each other, and maintaining -a xed relationship respectively with the ends of said several gears, a rotatable drive shaft within said housing to which said individual gears are non-rotatably aiixed, and a non-rotatable but axially movable shaft in said housing upon which said common gear is rotatably mounted but by means of which the said gear may be shifted axially, said shaft constituting in part said means for shifting.

6. In a pump, a housing formed in two joinable parts, each part having inlet and outlet chambers, a common gear in said housing, a pair of individual gears in said housing each of said gears in meshing relationship with said common gear, casing means in said housing maintaining respectively xed relationships with the outer ends of said common gear and said individual gears, and a partition means for dividing said housing so as to divide the inlet and outlet chambers of one of said parts from the inlet and outlet chambers of the other of said parts, said partition means comprising a plate held between the parts of said housing, and a rotatable section in said plate surrounding said common gear and having teeth meshing withthe teeth of said kcommon gear but slidable along its length, means for effecting a driving connection to at least one of said gears, and means for effecting a shifting of the axial relationships of said common gear and said individual gears whereby, inversely, to vary the -axial extent of the mashing of said common gear with each of said individual gears.

7. A vpropo-rtioning pump comprising in combination a housing with two sets of inlet and outlet chambers, a rotary, internally toothed gear, having liquid-tight connection with said housing peripherally, a pair of individual gears within said housing, said gears being coaxial, having external teeth, and having meshing relationship with the teeth of said first-mentioned gear, a shaft upon which said individual gears are rotatably mounted, casing means mounted on said shaft, and slidable within said housing, and partition means for dividing said sets of inlet and outlet openings, said partition means including a rotary element located in part between said individual gears, and having external teeth meshing with the teeth of said first-mentioned gear, said rotary element rotating with said first-mentioned gear, means for driving said first-mentioned gear, and means for shifting said shaft in an axial direction whereby inversely to vary the axial extent of the meshing of said individual gears respectively with said common gear. y

8. A proportioning pump comprising in combination a positive displacement rotary gear pump mechanism in which the iiuid being pumped is moved from the intlet side to the outlet side by the movement ofteeth o-f intermeshing gears in slidable contact with close fitting walls, a common gear, two coaxial individual gears in meshing relationship with said common gear, a partition adapted to close the cross section of the pump in a plane perpendicular to the pump axes, and intermediate the ends of said individual gears, said partition comprising a circular rotatable portion engaging the toothed surface o-f said common gear and being axially displaceable thereon, and means for effecting an axial displacement of said gears whereby the axial extent of the intermeshing of said common gear with said individual gears on' the opposite sides of said partition may be inversely varied, said pump having housing means with two sets of inlet and outlet chambers separated in part at least by said partition, whereby two separate streams may be delivered by said pump at any pre-determined volumetric ratio, which ratio m-ay be varied.

9. Aproportioning pumpfor pumpingtwo fluids separately and in adjustable proportions comprising in combination a positive displacement rotary gear pump mechanism in which the fluid being pumped is impelled from the inlet side to the outlet side by the movement of the teeth of intermeshing gears in sliding contact with clo-se fitting walls, intermeshing gears, means for shifting one of said gears axially with respect to the other, and partition means intermediate the ends -of both said gears, said partition means having a fixed axial position with respect to one of said gears, and interrupting the teeth of said one of said gears at the midpoint thereof, and being rotatable with the other of said gears, but slidable along the surface of said other gear to a plurality of axial positions.

10. A proportioning pump capable when operated at fixed speed of delivering two separate fluid streams at any predetermined volumetric Y interruption and thus to divide the housing into two separate compartments, said partition comprising a circularrotatable portion engaging the entire toothed surface of an'axial segmentof the first of said gears and'bein'g axially displaceable thereon, said partition having a circular'opening permitting passagetherethrough of the shaft of one of said gears, means for regulating theraxial position of said partition, together with said second gear with respect to said rst gear whereby the axial extent of the intermeshing of Asaid first gear with said second gear onthe opposite sides of said partition is regulated, inversely, two arcuate surface members, each adapted tobe in sliding contact with full axial extent of the top surfaces of the teeth of a different one of said gears, each over an arc substantially diametrically opposed to the line of intermeshing, two arcuate surface members, each adapted to'be in sliding contact with the opposite end portions of the top surfaces rof teeth of said second gear which extends beyond the respective ends ofrthe first gear, each over an arc passing through a prolongation of the line at which said top surfaces contact the inter-toothed valleys of said first gear, and .members in said housing adapted to provide planar walls perpendicular to the gear shafts and adjacent the lateral ends of the toothed valleys of said rst gear, end members in said housing adapted to provide planar walls perpendicular to the gear shafts and adjacent the lateral ends of the toothed valleys of said second gear, a barrier within said housing dividing each of the two compartments thereof into two cells, one on each side of yan imaginary plane passing through the axes of the two gear shafts, said cells being in communication with one another only by means of movable inter-tooth spaces enclosed between the toothed surfaces of the gears, the arcuate surface members, the partition, and the end members, said housing having inlet and outlet openings on each side of said partition, and means to drive one of said gears.

11. A proportioning pump comprising a housing, slidable casings, within said housing, said casings having a median portion which, with the housing provides an annular chamber, an internally toothed annular gear rotating in said housing and said chamber, and non-slidably heldl within the housing, the casings having lengthwise vanes on each side of the rotating member dividing the two ends of the casing into an inlet portion and an outlet portion, said gear having teeth on its exterior for driving the same by means of :an external gear, a shaft extending into the housing and secured to said casings, a pair of gears idly mounted on said shaft, one on each side of a partition, the teeth of said pair of gears meshing with the teeth of said first mentioned gear, a partition mounted within the firstmentioned gear and held against sliding movement on said shaft, said partition having teeth which match and enter the inter-tooth spaces within the first-mentioned gear, said partition being rotatable but non-slidable on said shaft, and means for moving the shaft lengthwise, thereby moving the partition and second-mentioned gears for the purpose described.

l2. In a proportioning pump of the gear type for pumping two iluids separately and in adjustable proportions, a pair of gear elements in mesh.- ing relationship, one of said gear elements being of greater axial extentl than the other, ,said gear element of greater axial extentV being divided into two parts, va partition element having a fixed relationship with said longer gear yat a pre-deterrminedl position but rotatable with. the shorter gear and having teeth maintaining a continuous inter-meshing relationship with all of the ,teeth of` theshorter gear, housing means having two sets of inlet and outlet,v chambers, one set being located on `each side of said partition element, and means for shifting said gears axially with respect to each other within said housing.

13. In combination with a'pumpv according to claim 1.means for severally equalizing the inlet and outlet pressures between the inlet and outlet chambers respectively of said sets; ycomprising displaceablebarrier elementsv separating each of said inlet chambers from its respective outlet chambers, each of said .barriers having substantially equaleiective areas exposed to the pres,-

sures'in said ichambersto which it is exposed, a

valve for ,controllingthe passage of, uid through one of said. chambers of each. set, and anoperativelconnectionbetween each Iof said barriers and ltsrespectivevalve.

14. In combination with a pump. according to claimY 7, means for severally equalizing the inlet and outlet pressures between the inletandoutlet chambers respectively of said sets, comprising dsplaneable barrier elements, separating each of said inlet chambers from itsv respective outlet chambers, each of saidbarriers having substantially equal effective areasexposed to the pres- .sures in said chambers to which it is exposed, a

valve for controlling the passage of fluid through one of said chambers. of each set, and an operative connection between each of said barriers and itsA respective valve.

15. In combination with a pump according to claim 8, means for severally equalizing the inlet and outlet pressures between the inlet and outlet chambersfrespectively of 4said sets. comprising'displaceable barrier elements separating each of said inlet chambers from itsV respective outlet chambers, each of sadbarriers having substantially equal effective areas exposed tothe. pressures in said chambers to which it isexposed a valve for controlling the passageof fluid through one of said chambers of .each set, .and an operativeconnection between each of said barriers and its respective yalve.

ROBERT V. BURT.

REFERENCES CITED vThe following references are of record in the file of this patent;

UNITED STATES PATENTS Number Name Date 1,602,740 Beehler Oct. 12, 1926 1,604,802 -Brenzinger Oct. 26, 1926 1,742,215 Pigott Jan. 7, 1930 2,052,419 Moore'et al Aug. 25, 1936 2,157,284 Egersdorfer May 9, 1939 2,293,126 Fersing Aug. 18, 1942 2,406,965 Orr Sept. 3, 1946 

